U.S. patent application number 10/590538 was filed with the patent office on 2007-07-26 for conductive paste for a multi-layered ceramic electronic component and a method for manufacturing a multi-layered unit for a multi-layered ceramic electronic component.
Invention is credited to Takeshi Nomura, Shigeki Satou.
Application Number | 20070172581 10/590538 |
Document ID | / |
Family ID | 34908804 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070172581 |
Kind Code |
A1 |
Satou; Shigeki ; et
al. |
July 26, 2007 |
Conductive paste for a multi-layered ceramic electronic component
and a method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component
Abstract
It is an object of the present invention to provide a method for
manufacturing a multi-layered unit for a multi-layered ceramic
electronic component which can reliably prevent short circuit
failure from occurring in a multi-layered ceramic electronic
component and form an electrode layer in a desired manner. A method
for manufacturing a multi-layered ceramic electronic component
includes a step of printing a conductive paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate on a ceramic green sheet
containing an acrylic system resin as a binder in a predetermined
pattern, thereby forming an electrode layer.
Inventors: |
Satou; Shigeki; (Tokyo,
JP) ; Nomura; Takeshi; (Tokyo, JP) |
Correspondence
Address: |
SEED INTELLECTUAL PROPERTY LAW GROUP PLLC
701 FIFTH AVE
SUITE 5400
SEATTLE
WA
98104
US
|
Family ID: |
34908804 |
Appl. No.: |
10/590538 |
Filed: |
February 23, 2005 |
PCT Filed: |
February 23, 2005 |
PCT NO: |
PCT/JP05/02881 |
371 Date: |
August 25, 2006 |
Current U.S.
Class: |
427/79 ; 427/256;
427/384 |
Current CPC
Class: |
C04B 35/6365 20130101;
C04B 2235/5454 20130101; B82Y 30/00 20130101; H01B 1/22 20130101;
C04B 2235/3215 20130101; C04B 2235/6582 20130101; H01G 4/30
20130101; C04B 35/63488 20130101; C04B 2235/3225 20130101; C04B
2235/3239 20130101; C04B 35/6264 20130101; C04B 35/632 20130101;
C04B 2235/6562 20130101; C04B 35/6261 20130101; C04B 2235/3208
20130101; H01G 4/12 20130101; C04B 2235/5445 20130101; C04B
2235/3206 20130101; C04B 2235/662 20130101; C04B 2235/3262
20130101; H01G 4/008 20130101; C04B 35/4682 20130101; C04B
2235/3436 20130101; C04B 2235/6025 20130101; C04B 2235/3454
20130101; C04B 35/63424 20130101; C04B 2235/6565 20130101; C04B
35/638 20130101; H01B 1/16 20130101; H01G 4/0085 20130101 |
Class at
Publication: |
427/079 ;
427/256; 427/384 |
International
Class: |
B05D 5/12 20060101
B05D005/12; B05D 3/02 20060101 B05D003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2004 |
JP |
2004-054722 |
Claims
1. A conductive paste containing a binder containing ethyl
cellulose having a weight average molecular weight of MW.sub.L and
ethyl cellulose having a weight average molecular weight of
MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and
X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a
range of 145,000 to 215,000 and at least one solvent selected from
the group consisting of isobornyl acetate, dihydroterpinyl methyl
ether, dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol
acetate.
2. A conductive paste in accordance with claim 1, wherein MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 155,000 to 205,000.
3. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component comprising a step of
printing a conductive paste containing a binder containing ethyl
cellulose having a weight average molecular weight of MW.sub.L and
ethyl cellulose having a weight average molecular weight of
MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and
X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a
range of 145,000 to 215,000 and at least one solvent selected from
the group consisting of isobornyl acetate, dihydroterpinyl methyl
ether, dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate on
a ceramic green sheet containing an acrylic system resin as a
binder in a predetermined pattern, thereby forming an electrode
layer.
4. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with claim
3, wherein MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 155,000 to
205,000.
5. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with claim
3, which further comprises a step of printing a dielectric paste
containing a binder containing ethyl cellulose having a weight
average molecular weight of MW.sub.L and ethyl cellulose having a
weight average molecular weight of MW.sub.H at a weight ratio of
X:(1-X), where MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 110,000 to
180,000 and at least one solvent selected from the group consisting
of isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate on
the ceramic green sheet in a complementary pattern to that of the
electrode layer after drying the electrode layer, thereby forming a
spacer layer.
6. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with claim
3, which further comprises a step of printing a dielectric paste
containing a binder containing ethyl cellulose having a weight
average molecular weight of MW.sub.L and ethyl cellulose having a
weight average molecular weight of MW.sub.H at a weight ratio of
X:(1-X), where MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 110,000 to
180,000 and at least one solvent selected from the group consisting
of isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate on
the ceramic green sheet in a complementary pattern to that of the
electrode layer prior to forming the electrode layer, thereby
forming a spacer layer.
7. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with any
one of claim 3, wherein the weight-average molecular weight of the
acrylic system resin is equal to or larger than 250,000 and equal
to or smaller than 500,000.
8. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with claim
7, wherein the weight-average molecular weight of the acrylic
system resin is equal to or larger than 450,000 and equal to or
smaller than 500,000.
9. A method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component in accordance with any
one of claim 3, wherein the acid value of the acrylic system resin
is equal to or larger than 5 mgKOH/g and equal to or smaller than
10 mgKOH/g.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a conductive paste for a
multi-layered ceramic electronic component and a method for
manufacturing a multi-layered unit for a multi-layered ceramic
electronic component, and particularly to a conductive paste for a
multi-layered ceramic electronic component which does not dissolve
a binder contained in a layer adjacent to an electrode layer of the
multi-layered ceramic electronic component and can reliably prevent
short circuit failure from occurring in a multi-layered ceramic
electronic component and a method for manufacturing a multi-layered
unit for a multi-layered ceramic electronic component which can
reliably prevent short circuit failure from occurring in a
multi-layered ceramic electronic component.
BACKGROUND OF THE INVENTION
[0002] Recently, the need to downsize various electronic devices
makes it necessary to downsize the electronic components
incorporated in the devices and improve the performance thereof.
Also in multi-layered ceramic electronic components, such as
multi-layered ceramic capacitors, it is strongly required to
increase the number of layers and make the laminated unit
thinner.
[0003] When a multi-layered ceramic electronic component as
typified by a multi-layered ceramic capacitor is to be
manufactured, ceramic powders, a binder such as an acrylic system
resin, a butyral resin or the like, a plasticizing agent such as a
phthalate ester, glycol, adipate ester, phosphate ester or the
like, and an organic solvent such as toluene, methyl ethyl ketone,
acetone or the like are mixed and dispersed, thereby preparing a
dielectric paste for a ceramic green sheet.
[0004] The dielectric paste is then applied onto a support sheet
made of polyethylene terephthalate (PET), polypropylene (PP) or the
like using an extrusion coater, a gravure coater or the like to
form a coating layer and the coating layer is heated to dryness,
thereby fabricating a ceramic green sheet.
[0005] Further, a conductive powder of nickel or the like and a
binder are dissolved into a solvent such as terpineol, thereby
preparing a conductive paste and the thus prepared conductive paste
is printed on the ceramic green sheet in a predetermined pattern
using a screen printing machine and dried, thereby forming an
electrode layer.
[0006] When the electrode layer has been formed, the ceramic green
sheet on which the electrode layer is formed is peeled off from the
support sheet to form a multi-layered unit including the ceramic
green sheet and the electrode layer. Then, a ceramic green chip is
formed by laminating a desired number of the multi-layered units to
form the laminated body, pressing the laminated body and dicing the
laminated body.
[0007] Finally, the binder is removed from the green chip, the
green chip is baked and an external electrode is formed, thereby
completing a multi-layered ceramic electronic component such as a
multi-layered ceramic capacitor.
[0008] At present, the need to downsize electronic components and
improve the performance thereof makes it necessary to set the
thickness of the ceramic green sheet determining the spacing
between layers of a multi-layered ceramic capacitor to be equal to
or smaller than 3 .mu.m or 2 .mu.m and to laminate three hundred or
more multi-layered units each including a ceramic green sheet and
an electrode layer.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0009] However, in the case where an electrode layer is formed by
printing a conductive paste prepared using terpineol, which is
highly popular as a solvent for a conductive paste, on a ceramic
green sheet formed using an acrylic system resin, which is the most
popular binder for a ceramic green sheet, the binder contained in
the ceramic green sheet is dissolved by terpineol contained in the
conductive paste and a ceramic green sheet is swollen or partially
dissolved, whereby pinholes and cracks are generated in the ceramic
green sheet to cause short circuit failure.
[0010] One proposed solution for these problems is to employ a
hydrocarbon system solvent such as kerosene, decane or the like as
the solvent for the conductive paste. However, since a hydrocarbon
system solvent such as kerosene, decane or the like does not
dissolve the binder component used for the conductive paste, it is
impossible to completely replace the conventional solvent such as
terpineol with a hydrocarbon system solvent such as kerosene,
decane or the like. Therefore, since the acrylic system resin
contained in the ceramic green sheet as a binder is still soluble
in the solvent contained in the conductive paste to some extent, it
is difficult to prevent generation of pinholes and cracks in the
ceramic green sheet in the case where the ceramic green sheet is
very thin, and since the viscosity of a hydrocarbon system solvent
such as kerosene, decane or the like is lower than that of
terpineol, it is difficult to control the viscosity of the
conductive paste.
[0011] Furthermore, Japanese Patent Application Laid Open No.
5-325633, Japanese Patent Application Laid Open No. 7-21833 and
Japanese Patent Application Laid Open No. 7-21832 propose a
conductive paste prepared using a hydrogenated terpineol such as
dihydroterpineol or a terpene system solvent such as
dihydroterpineol acetate instead of terpineol as a solvent.
However, since the acrylic system resin contained in the ceramic
green sheet as a binder is also soluble in a hydrogenated terpineol
such as dihydroterpineol or a terpene system solvent such as
dihydroterpineol acetate to some extent, it is difficult to prevent
generation of pinholes and cracks in a ceramic green sheet in the
case where the ceramic green sheet is very thin.
[0012] Further, Japanese Patent Application Laid Open No.
2002-270456 discloses a multi-layered ceramic electronic component
fabricated by printing a conductive paste containing isobornyl
acetate as a solvent, which hardly dissolves a butyral system
resin, on a ceramic green sheet containing a butyral system resin
as a binder, thereby forming an electrode layer and discloses that
it is preferable to employ ethyl cellulose as a binder of the
conductive paste. However, since a conductive paste containing
ethyl cellulose as a binder and isobornyl acetate as a solvent has
low viscosity and high fluidity, when the conductive paste is
printed on a ceramic green sheet using a screen printing machine,
the conductive paste leaks from a screen printing plate and the
electrode layer cannot be printed in a desired manner. Further, the
thus printed electrode layer tends to blot.
[0013] It is therefore an object of the present invention to
provide a conductive paste for a multi-layered ceramic electronic
component which does not dissolve a binder contained in a layer
adjacent to an electrode layer of the multi-layered ceramic
electronic component, can reliably prevent short circuit failure
from occurring in a multi-layered ceramic electronic component and
has excellent printability.
[0014] It is another object of the present invention to provide a
method for manufacturing a multi-layered unit for a multi-layered
ceramic electronic component which can reliably prevent short
circuit failure from occurring in a multi-layered ceramic
electronic component and form an electrode layer in a desired
manner.
MEANS FOR SOLVING THE PROBLEMS
[0015] The inventors of the present invention vigorously pursued a
study for accomplishing the above objects and, as a result, made
the discovery that in the case where a conductive paste was
prepared using a binder containing ethyl cellulose having a weight
average molecular weight of MW.sub.L and ethyl cellulose having a
weight average molecular weight of MW.sub.H at a weight ratio of
X:(1-X), where MW.sub.L, MW.sub.H and X were selected so that X
MW.sub.L+(1-X)*MW.sub.H fell within a range of 145,000 to 215,000,
and at least one kind of solvent selected from the group consisting
of isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol, I-perillyl
alcohol and acetoxy-methoxyethoxy-cyclohexanol acetate, it was
possible to prepare a conductive paste having a viscosity suitable
for printing and dissolve a binder of the conductive paste in a
binder in a desired manner and even when the conductive paste was
printed on a ceramic green sheet containing an acrylic system resin
as a binder, the binder contained in the ceramic green sheet was
not dissolved in the solvent contained in the dielectric paste and
it was therefore possible to reliably prevent generation of
pinholes and cracks in the ceramic green sheet even in the case
where the ceramic green sheet was very thin.
[0016] The present invention is based on these findings and
therefore, the objects of the present invention can be accomplished
by a conductive paste containing a binder containing ethyl
cellulose having a weight average molecular weight of MW.sub.L and
ethyl cellulose having a weight average molecular weight of
MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and
X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a
range of 145,000 to 215,000 and at least one kind of solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate.
[0017] The objects of the present invention can be also
accomplished by a method for manufacturing a multi-layered unit for
a multi-layered ceramic electronic component comprising a step of
printing a conductive paste containing a binder containing ethyl
cellulose having a weight average molecular weight of MW.sub.L and
ethyl cellulose having a weight average molecular weight of
MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and
X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a
range of 145,000 to 215,000 and at least one solvent selected from
the group consisting of isobornyl acetate, dihydroterpinyl methyl
ether, dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate on
a ceramic green sheet containing an acrylic system resin as a
binder in a predetermined pattern, thereby forming an electrode
layer.
[0018] According to the present invention, it is possible to
prepare a conductive paste having a viscosity suitable for printing
and form an electrode layer in a desired manner. Further, according
to the present invention, even when the conductive paste is printed
on a very thin ceramic green sheet containing an acrylic system
resin as a binder, since the binder contained in the ceramic green
sheet is not dissolved in the solvent contained in the dielectric
paste, it is possible to reliably prevent the ceramic green sheet
from being swollen or partially dissolved and it is therefore
possible to reliably prevent generation of pinholes and cracks in
the ceramic green sheet even in the case where the ceramic green
sheet is very thin.
[0019] In the present invention, it is preferable for MW.sub.L,
MW.sub.H and X to be selected so that X*MW.sub.L+(1-X)*MW.sub.H
falls within a range of 155,000 to 205,000.
[0020] In the present invention, it is preferable for the
weight-average molecular weight of an acrylic system resin
contained in the ceramic green sheet as a binder to be equal to or
larger than 250,000 and equal to or smaller than 500,000 and it is
more preferable for the weight-average molecular weight of an
acrylic system resin to be equal to or larger than 450,000 and
equal to or smaller than 500,000.
[0021] In the present invention, it is preferable for the acid
value of an acrylic system resin contained in the ceramic green
sheet as a binder to be equal to or larger than 5 mgKOH/g and equal
to or smaller than 10 mgKOH/g and in the case where an acrylic
system resin whose acid value is equal to or larger than 5 mgKOH/g
and equal to or smaller than 10 mgKOH/g is employed as the binder
of a ceramic green sheet, it is possible to prepare a dielectric
paste for forming a ceramic green sheet so as to have a desired
viscosity.
[0022] In a preferred aspect of the present invention, prior to
forming the electrode layer or after forming and drying the
electrode layer, a dielectric paste containing a binder containing
ethyl cellulose having a weight average molecular weight of
MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate is printed on a ceramic
green sheet in a complementary pattern to that of the electrode
layer, thereby forming a spacer layer.
[0023] According to this preferred aspect of the present invention,
since a spacer layer is formed on a ceramic green sheet in a
complementary pattern to that of the electrode layer, it is
possible to prevent a step from being formed between the surface of
the electrode layer and the surface of the ceramic green sheet
where no electrode layer is formed. Therefore, even in the case of
laminating a number of multi-layered units each including a ceramic
green sheet and an electrode layer and fabricating a multi-layered
electronic component such as a multi-layered ceramic capacitor, it
is possible to effectively prevent the thus fabricated
multi-layered electronic component from being deformed and also
effectively prevent delamination of layers from occurring.
[0024] Further, since a mixed solvent of terpineol and kerosene,
dihydroterpineol, terpineol or like, which is popular as a solvent
for a dielectric paste for forming a spacer layer, dissolves an
acrylic system resin contained in a ceramic green sheet as a
binder, when a spacer layer is formed on a ceramic green sheet, the
ceramic green sheet is swollen or partially dissolved, whereby
voids are generated at the interface between the ceramic green
sheet and the spacer layer or fissures or wrinkles are generated on
the surface of the spacer layer. As a result, in the case where a
multi-layered ceramic capacitor is fabricated by laminating a
number of multi-layered units to fabricate a laminated body and
baking the laminated body, voids are generated in the multi-layered
ceramic capacitor. Further, in the case where fissures or wrinkles
are generated on the surface of the spacer layer, since the
portions of the spacer layer where fissures or wrinkles are
generated tend to drop off, when a number of multi-layered units
are laminated to fabricate a laminated body, the portions of the
spacer layer where fissures or wrinkles are generated mix into the
laminated body as a foreign substance, thereby causing internal
defects in the multi-layered ceramic capacitor and generating voids
at portions where the spacer layer is missing. However, according
to this preferred aspect of the present invention, since a
dielectric paste for forming a spacer layer contains a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate and the solvent selected
from the group consisting of isobornyl acetate, dihydroterpinyl
methyl ether, dihydroterpinyl oxyethanol, terpinyl methyl ether,
terpinyl oxyethanol, d-dihydrocarveol, I-menthyl acetate,
I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves an
acrylic system resin contained in a ceramic green sheet as a
binder, it is possible to reliably prevent the ceramic green sheet
from being swollen or partially dissolved so as to generate voids
at the interface between the ceramic green sheet and the spacer
layer or generate fissures or wrinkles on the surface of the spacer
layer, and it is therefore possible to reliably prevent voids from
being generated in a multi-layered ceramic electronic component
such as a multi-layered ceramic capacitor.
[0025] Moreover, since a dielectric paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate has a viscosity suitable
for printing, a spacer layer can be formed on a ceramic green sheet
in a desired manner by printing a dielectric paste on the ceramic
green sheet in a complimentary pattern to that of an electrode
layer.
[0026] Further, in a study done by the inventors of the present
invention, it was found that in the case of printing a conductive
paste on a very thin ceramic green sheet to form an electrode
layer, the solvent contained in the conductive paste for forming
the electrode layer dissolved or swelled a binder component
contained in the ceramic green sheet and, on the other hand, the
conductive paste permeated into the ceramic green sheet, thereby
causing short circuit failure and that, therefore, it was
preferable to form the electrode layer on a support sheet
separately from the ceramic green sheet and bond it onto the
surface of the ceramic green sheet via an adhesive layer after
drying it. However, in the case where the electrode layer is formed
on the support sheet separately from the ceramic green sheet in
this manner, in order to make the support sheet easy to peel off
from the electrode layer, it is preferable to form a release layer
containing the same binder as that contained in the ceramic green
sheet on the support sheet and print a conductive paste on the
release layer, thereby forming an electrode layer. Even in the case
of printing a conductive paste on the release layer containing the
same binder as that contained in the ceramic green sheet to form an
electrode layer, when the release layer contains an acrylic system
resin as a binder and the conductive paste contains terpineol as a
solvent, the binder contained in the release layer is dissolved by
the solvent contained in the conductive paste so that the release
layer is swollen or partially dissolved, whereby voids are
generated at the interface between the release layer and the
electrode layer or fissures or wrinkles are generated on the
surface of the electrode layer. As a result, in the case where a
multi-layered ceramic capacitor is fabricated by laminating a
number of multi-layered units to fabricate a laminated body and
baking the laminated body, voids are generated in the multi-layered
ceramic capacitor. Furthermore, in the case where fissures or
wrinkles are generated on the surface of the electrode layer, since
the portions of the electrode layer where fissures or wrinkles are
generated tend drop off, when a number of multi-layered units are
laminated to fabricate a laminated body, the portions of the
electrode layer where fissures or wrinkles are generated mix into
the laminated body as a foreign substance, thereby causing internal
defects in the multi-layered ceramic capacitor and generating voids
at portions where the electrode layer was missing.
[0027] However, according to the present invention, the electrode
layer is formed using the conductive paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate and the solvent selected
from the group consisting of isobornyl acetate, dihydroterpinyl
methyl ether, dihydroterpinyl oxyethanol, terpinyl methyl ether,
terpinyl oxyethanol, d-dihydrocarveol, I-menthyl acetate,
I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves the
acrylic system resin contained in the ceramic green sheet as a
binder. Therefore, even in the case of forming a release layer
containing the same binder as that contained in the ceramic green
sheet and printing a conductive paste on the release layer to form
an electrode layer it is possible to reliably prevent the release
layer from being swollen or partially dissolved so as to generate
voids at the interface between the release layer and the electrode
layer or generate fissures or wrinkles on the surface of the
electrode layer and it is therefore possible to effectively prevent
defects from being generated in a multi-layered ceramic electronic
component such as a multi-layered ceramic capacitor.
TECHNICAL ADVANTAGES OF THE INVENTION
[0028] According to the present invention, it is possible to
provide a conductive paste for a multi-layered ceramic electronic
component which does not dissolve a binder contained in a layer
adjacent to an electrode layer of the multi-layered ceramic
electronic component, can reliably prevent short circuit failure
from occurring in a multi-layered ceramic electronic component and
has excellent printability.
[0029] Further, according to the present invention, it is possible
to provide a method for manufacturing a multi-layered ceramic
electronic component which can reliably prevent short circuit
failure from occurring in a multi-layered ceramic electronic
component and form an electrode layer in a desired manner.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] In a preferred embodiment of the present invention, a
dielectric paste for a ceramic green sheet which contains an
acrylic system resin as a binder is first prepared and is applied
onto a long support sheet using an extrusion coater or a wire bar
coater, thereby forming a coating layer.
[0031] A dielectric paste for forming a ceramic green sheet is
normally prepared by kneading a dielectric material (ceramic
powder) and an organic vehicle obtained by dissolving an acrylic
system resin into an organic solvent.
[0032] It is preferable for the weight-average molecular weight of
the acrylic system resin to be equal to or larger than 250,000 and
equal to or smaller than 500,000 and it is more preferable for the
weight-average molecular weight of the acrylic system resin to be
equal to or larger than 450,000 and equal to or smaller than
500,000.
[0033] Further, it is preferable for the acid value of the acrylic
system resin to be equal to or larger than 5 mgKOH/gram and equal
to or smaller than 10 mgKOH/gram.
[0034] An organic solvent used for preparing the organic vehicle is
not particularly limited and an organic solvent such as terpineol,
butyl carbitol, acetone, toluene, ethyl acetate and the like can be
used for preparing the organic vehicle.
[0035] The dielectric material can be selected from among various
compounds capable of forming a composite oxide or oxide, such as a
carbonate, nitrate, hydroxide, organic metallic compound and the
like and mixtures thereof. The dielectric material is normally used
in the form of a powder whose average particle diameter is about
0.1 .mu.m to about 3.0 .mu.m. The particle diameter of the
dielectric raw material is preferably smaller than the thickness of
the ceramic green sheet.
[0036] The amounts of the respective constituents contained in the
dielectric paste is not particularly limited and the dielectric
paste may be prepared so as to contain 100 weight parts of a
dielectric material, about 2.5 weight part to about 10 weight parts
of an acrylic system resin and about 50 weight parts to about 300
weight parts of a solvent, for example.
[0037] As occasion demands, the dielectric paste may contain
additives selected from among various dispersing agents,
plasticizing agents, antistatic auxiliary agent, releasing agent,
wetting agent and the like. In the case of adding these additives
to the dielectric paste, it is preferable to set the total content
to be equal to or less than about 20 weight %.
[0038] As a support sheet coated with the dielectric paste, a
polyethylene terephthalate film is employed, for example, and the
surface of the support sheet may be coated with a silicon resin, an
alkyd resin or the like in order to improve the releasability
thereof.
[0039] The coating layer is then dried at a temperature of about
50.degree. C. to about 100.degree. C. for about 1 to about 20
minutes, whereby a ceramic green sheet is formed on the support
sheet.
[0040] In the present invention, the thickness of the ceramic green
sheet after drying is preferably equal to or thinner than 3 .mu.m
and more preferably equal to or thinner than 1.5 .mu.m.
[0041] Next, a conductive paste for forming an electrode layer is
printed on the ceramic green sheet formed on the long support sheet
in a predetermined pattern using a screen printing machine, a
gravure printing machine or the like.
[0042] It is preferable to form the electrode layer so as to have a
dry thickness of about 0.1 .mu.m to about 5 .mu.m and it is more
preferable to form the electrode layer so as to have a dry
thickness of about 0.1 .mu.m to about 1.5 .mu.m.
[0043] The conductive paste usable for forming an electrode layer
is prepared by kneading a conductive material containing any of
various conductive metals or alloys, any of various oxides which
will form a conductive material containing any of various
conductive metals or alloys after baking, an organic metal
compound, resinate or the like, and an organic vehicle prepared by
dissolving a butyral system resin in an organic solvent.
[0044] In this preferred embodiment of the present invention, the
conductive paste contains a binder containing ethyl cellulose
having a weight average molecular weight of MW.sub.L and ethyl
cellulose having a weight average molecular weight of MW.sub.H at a
weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and X are
selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a range of
145,000 to 215,000 and at least one solvent selected from the group
consisting of isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol
acetate.
[0045] Since the solvent selected from the group consisting of
isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
hardly dissolves the acrylic system resin contained in a ceramic
green sheet as a binder, even in the case of printing the
conductive paste on a very thin ceramic green sheet, thereby
forming an electrode layer, it is possible to effectively prevent
the binder contained in the ceramic green sheet from being
dissolved by the solvent contained in the conductive paste, whereby
the ceramic green sheet is swollen or partially dissolved. It is
therefore possible to reliably prevent generation of pinholes and
cracks in the ceramic green sheet even in the case where the
ceramic green sheet is very thin.
[0046] Further, since a conductive paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate has a viscosity suitable
for printing, it is possible to print a conductive paste on a
ceramic green sheet using a screen printing machine, a gravure
printing machine or the like to form an electrode layer in a
predetermined pattern in a desired manner.
[0047] Preferably, MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 155,000 to
205,000.
[0048] As the conductive material used for preparing the conductive
paste, Ni, Ni alloy or the mixture thereof is preferably used. The
shape of the conductive material is not particularly limited. The
conductive material particles may have a spherical shape or a
scale-like shape, or the conductive material may contain spherical
conductive material particles and scale-like conductive material
particles. The average particle diameter of the conductive material
is not particularly limited but a conductive material having an
average particle diameter of about 0.1 .mu.m to about 2 .mu.m is
normally used for preparing the electrode paste and the conductive
material having an average particle diameter of about 0.2 .mu.m to
about 1 .mu.m is preferably used for preparing the electrode
paste.
[0049] The conductive paste preferably contains the binder in an
amount about 2.5 weight parts to about 20 weight parts with respect
to 100 weight parts of the conductive material.
[0050] The content of the solvent is preferably about 40 weight %
to about 60 weight % with respect to the weight of the conductive
paste.
[0051] In order to improve adhesion property, it is preferable for
the conductive paste to contain a plasticizing agent. The
plasticizing agent contained in the conductive paste is not
particularly limited and illustrative examples thereof include
phthalate ester, adipic acid, phosphate ester, glycols and the
like. The conductive paste contains the plasticizing agent
preferably in an amount of about 10 weight % to about 300 weight %
with respect to 100 weight parts of the binder, more preferably in
an amount of about 10 weight parts to about 200 weight parts. In
the case where the amount of the plasticizing agent added to the
conductive paste is too large, the strength of the electrode layer
tends to be markedly lower.
[0052] As occasion demands, the conductive paste may contain
additives selected from among various dispersing agents accessory
ingredient compounds and the like.
[0053] In the present invention, preferably, prior to forming an
electrode layer or after forming an electrode layer and drying it,
a dielectric paste adapted for forming a spacer layer and
containing a binder containing ethyl cellulose having a weight
average molecular weight of MW.sub.L and ethyl cellulose having a
weight average molecular weight of MW.sub.H at a weight ratio of
X:(1-X), where MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 110,000 to
180,000 and at least one solvent selected from the group consisting
of isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate is
printed on the surface of a ceramic green sheet in a complementary
pattern to that of the electrode layer using a screen printing
machine, a gravure printing machine or the like, thereby forming a
spacer layer.
[0054] In the case where a spacer layer is formed on the surface of
a ceramic green sheet in a complementary pattern to that of the
electrode layer in this manner, it is possible to prevent a step
from being formed between the surface of the electrode layer and
the surface of the ceramic green sheet where no electrode layer is
formed. Therefore, even in the case of laminating a number of
multi-layered units each including a ceramic green sheet and an
electrode layer and fabricating a multi-layered electronic
component such as a multi-layered ceramic capacitor, it is possible
to effectively prevent the thus fabricated multi-layered electronic
component from being deformed and also effectively prevent
delamination of layers from occurring.
[0055] Furthermore, as described above, since the solvent selected
from the group consisting of isobornyl acetate, dihydroterpinyl
methyl ether, dihydroterpinyl oxyethanol, terpinyl methyl ether,
terpinyl oxyethanol, d-dihydrocarveol, I-menthyl acetate,
I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves the
acrylic system resin contained in the ceramic green sheet as a
binder, it is possible to reliably prevent the ceramic green sheet
from being swollen or partially dissolved so as to generate voids
at the interface between the ceramic green sheet and the spacer
layer or generate fissures or wrinkles on the surface of the spacer
layer.
[0056] Moreover, since the dielectric paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate has a viscosity suitable
for printing, a spacer layer can be formed on a ceramic green sheet
in a complimentary pattern to that of the electrode layer in a
desired manner using a screen printing machine, a gravure printing
machine or the like.
[0057] In this embodiment, the dielectric paste for forming the
spacer layer is prepared in the similar manner to the dielectric
paste for forming the ceramic green sheet except that different
binder and solvent are used.
[0058] Then, the electrode layer or the electrode layer and the
spacer layer are dried and a multi-layered unit including the
ceramic green sheet and electrode layer or the electrode layer and
the spacer layer laminated on the support sheet is fabricated.
[0059] When a multi-layered ceramic capacitor is to be fabricated,
the support sheet is peeled off from the ceramic green sheet of the
multi-layered unit and the multi-layered unit is diced to
predetermined dimensions. Then, a predetermined number of the
multi-layered units are laminated on the outer layer of a
multi-layered ceramic capacitor and the other outer layer of a
multi-layered ceramic capacitor is further laminated on the
multi-layered units, thereby fabricating a laminated body. Next,
the thus obtained laminated body is press molded and diced to
predetermined dimensions, thereby fabricating ceramic green
chips.
[0060] The thus fabricated ceramic green chips are placed in a
reducing gas atmosphere so that the binder is removed therefrom and
the ceramic green chips are baked.
[0061] Necessary external electrodes are then attached to the thus
baked ceramic green chip, thereby manufacturing a multi-layered
ceramic capacitor.
[0062] According to this embodiment, since the electrode layer is
formed by printing the conductive paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate on the ceramic green
sheet containing an acrylic system resin as a binder in a
predetermined pattern and the solvent selected from the group
consisting of isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
hardly dissolves the acrylic system resin contained in a ceramic
green sheet as a binder. As a result, even in the case of printing
the conductive paste on a very thin ceramic green sheet, thereby
forming an electrode layer, it is possible to reliably prevent the
binder contained in the ceramic green sheet from being dissolved by
the solvent contained in the conductive paste and the ceramic green
sheet from being swollen or partially dissolved. Therefore, even in
the case where a ceramic green sheet is very thin, it is possible
to effectively prevent generation of pinholes or cracks in the
ceramic green sheet and it is therefore possible to effectively
prevent short circuit failure from occurring in a multi-layered
ceramic capacitor fabricated by laminating a number of
multi-layered units.
[0063] Further, according to this embodiment, the spacer layer is
formed by printing the dielectric paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate on the ceramic green
sheet containing an acrylic system resin as a binder in a
complementary pattern to that of the electrode layer and the
solvent selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves the
acrylic system resin contained in a ceramic green sheet as a
binder. As a result, even in the case of printing the dielectric
paste on a very thin ceramic green sheet, thereby forming a spacer
layer, it is possible to reliably prevent the binder contained in
the ceramic green sheet from being dissolved by the solvent
contained in the dielectric paste and the ceramic green sheet from
being swollen or partially dissolved so as to generate voids at the
interface between the ceramic green sheet and the spacer layer or
generate fissures or wrinkles on the surface of the spacer layer.
Therefore, in the case where a multi-layered ceramic capacitor is
fabricated by laminating a number of multi-layered units each
including a ceramic green sheet and an electrode layer, it is
possible to reliably prevent voids from being generated in the
multi-layered ceramic capacitor and it is also possible to reliably
prevent the portions of the spacer layer where fissures or wrinkles
are generated from dropping off during lamination of a number of
the multi-layered units to fabricate the laminated body and mixing
into the laminated body as a foreign substance so as to cause
internal defects in the multi-layered ceramic capacitor.
[0064] In another preferred embodiment of the present invention, a
second support sheet is provided separately from the long support
sheet used for forming the ceramic green sheet and the surface of
the long second support sheet is coated using a wire bar coater or
the like with a dielectric paste containing particles of a
dielectric material having substantially the same composition as
that of the dielectric material contained in the ceramic green
sheet and the same binder as that contained in the ceramic green
sheet, thereby forming a coating layer and the coating layer is
dried to form a release layer.
[0065] As the second support sheet, a polyethylene terephthalate
film is employed, for example, and the surface of the second
support sheet may be coated with a silicon resin, an alkyd resin or
the like in order to improve the releasability thereof.
[0066] The thickness of the release layer is preferably equal to or
thinner than that of an electrode layer, more preferably equal to
or thinner than about 60% of the electrode layer thickness and most
preferably equal to or thinner than about 30% of the electrode
layer thickness.
[0067] After the release layer has been dried, the conductive paste
for an electrode layer prepared in the above described manner is
printed on the surface of the release layer in a predetermined
pattern using a screen printing machine, a gravure printing machine
or the like, thereby forming an electrode layer.
[0068] It is preferable to form the electrode layer so as to have a
thickness of about 0.1 .mu.m to about 5 .mu.m and it is more
preferable to form the electrode layer so as to have a thickness of
about 0.1 .mu.m to about 1.5 .mu.m.
[0069] In this embodiment, the conductive paste contains a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate.
[0070] Since the solvent selected from the group consisting of
isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
hardly dissolves an acrylic system resin contained in a ceramic
green sheet as a binder, even in the case of forming a release
layer containing the same binder as that of the ceramic green sheet
and printing the conductive paste on the release layer to form an
electrode layer, it is possible to effectively prevent the release
layer from being swollen or partially dissolved so as to generate
voids at the interface between the release layer and the electrode
layer or generate fissures or wrinkles on the surface of the
electrode layer.
[0071] Further, since the conductive paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 145,000 to 215,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate has a viscosity suitable
for printing, an electrode layer can be formed on the release layer
in a predetermined pattern using a screen printing machine, a
gravure printing machine or the like in a desired manner.
[0072] Preferably, MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 155,000 to
205,000.
[0073] In the present invention, preferably, prior to forming an
electrode layer or after forming an electrode layer and drying it,
a dielectric paste containing a binder containing ethyl cellulose
having a weight average molecular weight of MW.sub.L and ethyl
cellulose having a weight average molecular weight of MW.sub.H at a
weight ratio of X:(1-X), where MW.sub.L, MW.sub.H and X are
selected so that X*MW.sub.L+(1-X)*MW.sub.H falls within a range of
110,000 to 180,000 and at least one solvent selected from the group
consisting of isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
and prepared in the above described manner is printed on the
surface of the release layer in a complementary pattern to that of
the electrode layer using a screen printing machine, a gravure
printing machine or the like, thereby forming a spacer layer.
[0074] In the case where the spacer layer is formed on the surface
of a release layer in a complementary pattern to that of the
electrode layer in this manner, it is possible to prevent a step
from being formed between the surface of the electrode layer and
the surface of the release layer where no electrode layer is
formed. Therefore, even in the case of laminating a number of
multi-layered units each including a ceramic green sheet and an
electrode layer and fabricating a multi-layered electronic
component such as a multi-layered ceramic capacitor, it is possible
to effectively prevent the thus fabricated multi-layered electronic
component from being deformed and also effectively prevent
delamination of layers from occurring.
[0075] Further, as described above, since the solvent selected from
the group consisting of isobornyl acetate, dihydroterpinyl methyl
ether, dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
hardly dissolves the acrylic system resin contained in the ceramic
green sheet as a binder, even in the case of forming the release
layer containing the same binder as that of the ceramic green sheet
and printing a dielectric paste on the release layer to form a
spacer layer, it is possible to effectively prevent the release
layer from being swollen or partially dissolved so as to generate
voids at the interface between the release layer and the spacer
layer or generate fissures or wrinkles on the surface of the spacer
layer.
[0076] Further, since the dielectric paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate has a viscosity suitable
for printing, a spacer layer can be formed on the surface of the
release layer in a complementary pattern to that of the electrode
layer using a screen printing machine, a gravure printing machine
or the like in a desired manner.
[0077] Further, a long third support sheet is provided and the
surface of the third support sheet is coated with an adhesive agent
solution using a bar coater, an extrusion coater, a reverse coater,
a dip coater, a kiss coater or the like and the coating layer is
dried, thereby forming an adhesive layer.
[0078] It is preferable for the adhesive agent solution to contain
a binder belonging to the same group as that the binder contained
in the ceramic green sheet belongs to, particles of a dielectric
material having substantially the same composition as that of
dielectric particles contained in the ceramic green sheet, a
plasticizing agent, an antistatic agent and a release agent.
[0079] It is preferable to form an adhesive layer so as to have a
thickness thinner than about 0.3 .mu.m, more preferable to form it
so as to have a thickness of about 0.02 .mu.m to about 0.3 .mu.m
and particularly preferable to form it so as to have a thickness of
about 0.02 .mu.m to about 0.2 .mu.m.
[0080] The adhesive layer formed on the long third support sheet in
this manner is bonded onto the surface of the electrode layer or
the surfaces of the electrode layer and the spacer layer formed on
the long second support sheet or the surface of the ceramic green
sheet formed on the support sheet and the third support sheet then
is peeled off from the adhesive layer, whereby the adhesive layer
is transferred onto the surface of the electrode layer or the
surfaces of the electrode layer and the spacer layer or the surface
of the ceramic green sheet.
[0081] In the case where the adhesive layer is transferred onto the
surface of the electrode layer or the surfaces of the electrode
layer and the spacer layer, the ceramic green sheet formed on the
long support sheet is bonded onto the adhesive layer and the first
support sheet is peeled off from the ceramic green sheet so that
the ceramic green sheet is transferred onto the surface of the
adhesive layer, thereby fabricating a multi-layered unit including
the ceramic green sheet and the electrode layer or the electrode
layer and the spacer layer.
[0082] An adhesive layer is transferred onto the surface of the
ceramic green sheet of the thus fabricated multi-layered unit in a
similar manner to that of transferring the adhesive layer onto the
surface of the electrode layer or the surfaces of the electrode
layer and the spacer layer and the multi-layered unit including the
adhesive layer transferred onto the surface thereof is diced to
predetermined dimensions.
[0083] Similarly, a predetermined number of multi-layered units
each including the adhesive layer transferred onto the surface
thereof are fabricated and the predetermined number of
multi-layered units are laminated, thereby fabricating a
multi-layered block.
[0084] When a multi-layered block is to be fabricated, the
multi-layered unit is first positioned on a support formed of
polyethylene terephthalate or the like in such a manner that the
adhesive layer transferred onto the surface of the multi-layered
unit comes into contact with the support and the multi-layered unit
is pressed by a pressing machine or the like, whereby the
multi-layered unit is bonded onto the support via the adhesive
layer.
[0085] Afterwards, the second support sheet is peeled off from the
release layer and the multi-layered unit is laminated on the
support.
[0086] Then, a new multi-layered unit is positioned on the surface
of the release layer of the multi-layered unit laminated on the
support in such a manner that an adhesive layer formed on the new
multi-layered unit comes into contact with the surface of the
release layer and the multi-layered unit is pressed using a
pressing machine or the like, whereby the new multi-layered unit is
laminated on the surface of the release layer of the multi-layered
unit laminated on the support via the adhesive layer. Afterwards,
the second support sheet is peeled off from the release layer of
the new multi-layered unit.
[0087] Similar processes are repeated, thereby fabricating a
multi-layered block including a predetermined number of the
laminated multi-layered units.
[0088] On the other hand, in the case where the adhesive layer is
transferred onto the surface of the ceramic green sheet, the
electrode layer or the electrode layer and the spacer layer formed
on the second support sheet are bonded onto the adhesive layer and
then, the second support sheet is peeled off from the release
layer, the electrode layer or the electrode layer and the spacer
layer and the release layer are transferred onto the surface of the
adhesive layer. Thus, a multi-layered unit including the ceramic
green sheet and the electrode layer is fabricated.
[0089] An adhesive layer is transferred onto the surface of the
release layer of the thus obtained multi-layered unit in a similar
manner to that of transferring the adhesive layer onto the surface
of the ceramic green sheet and the multi-layered unit including the
adhesive layer transferred onto the surface thereof is diced to
predetermined dimensions.
[0090] Similarly, a predetermined number of multi-layered units
each including the adhesive layer transferred onto the surface
thereof are fabricated and the predetermined number of
multi-layered units are laminated, thereby fabricating a
multi-layered block.
[0091] When a multi-layered block is to be fabricated, the
multi-layered unit is first positioned on a support formed of
polyethylene terephthalate or the like in such a manner that the
adhesive layer transferred onto the surface of the multi-layered
unit comes into contact with the support and the multi-layered unit
is pressed by a pressing machine or the like, whereby the
multi-layered unit is bonded onto the support via the adhesive
layer.
[0092] Afterwards, the support sheet is peeled off from the ceramic
green sheet and the multi-layered unit is laminated on the
support.
[0093] Then, a new multi-layered unit is positioned on the surface
of the ceramic green sheet of the multi-layered unit laminated on
the support in such a manner that an adhesive layer formed on the
new multi-layered unit comes into contact with the surface of the
ceramic green sheet and the multi-layered unit is pressed using a
pressing machine or the like, whereby the new multi-layered unit is
laminated on the surface of the ceramic green sheet of the
multi-layered unit laminated on the support via the adhesive layer.
Afterwards, the support sheet is peeled off from the release layer
of the new multi-layered unit.
[0094] Similar processes are repeated, thereby fabricating a
multi-layered block including a predetermined number of the
laminated multi-layered units.
[0095] The thus fabricated multi-layered block including the
predetermined number of the laminated multi-layered units is
laminated on the outer layer of a multi-layered ceramic capacitor
and the other outer layer of a multi-layered ceramic capacitor is
further laminated on the multi-layered block, thereby fabricating a
laminated body. Next, the thus obtained laminated body is press
molded and diced to predetermined dimensions, thereby fabricating a
number of ceramic green chips.
[0096] The thus fabricated ceramic green chips are placed in a
reducing gas atmosphere so that the binder is removed therefrom and
the ceramic green chips are baked.
[0097] Necessary external electrodes are then attached to the thus
baked ceramic green chip, thereby manufacturing a multi-layered
ceramic capacitor.
[0098] According to this preferred embodiment, since the electrode
layer and the spacer layer formed on the second support sheet are
dried and then bonded onto the surface of the ceramic green sheet
via the adhesive layer, unlike in the case of printing a conductive
paste on the surface of the ceramic green sheet to form an
electrode layer and printing a dielectric paste on the surface of
the ceramic green sheet to form a spacer layer, it is possible to
prevent the conductive paste and the dielectric paste from
permeating into the ceramic green sheet and it is therefore
possible to laminate the electrode layer and the spacer layer on
the surface of the ceramic green sheet in a desired manner.
[0099] Furthermore, according to this preferred embodiment, the
electrode layer is formed using the conductive paste containing a
binder containing ethyl cellulose having a weight average molecular
weight of MW.sub.L and ethyl cellulose having a weight average
molecular weight of MW.sub.H at a weight ratio of X:(1-X), where
MW.sub.L, MW.sub.H and X are selected so that
X*MW.sub.L+(1-X)*MW.sub.H falls within a range of 145,000 to
215,000 and at least one solvent selected from the group consisting
of isobornyl acetate, dihydroterpinyl methyl ether, dihydroterpinyl
oxyethanol, terpinyl methyl ether, terpinyl oxyethanol,
d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol and acetoxy-methoxyethoxy-cyclohexanol acetate
and the solvent selected from the group consisting of isobornyl
acetate, dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol,
terpinyl methyl ether, terpinyl oxyethanol, d-dihydrocarveol,
I-menthyl acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves an
acrylic system resin contained in a ceramic green sheet as a
binder. As a result, even in the case of forming the release layer
containing the same binder as that contained in a ceramic green
sheet and printing the conductive paste on the release layer,
thereby forming an electrode layer, it is possible to effectively
prevent the release layer from being swollen or partially dissolved
so as to generate pinholes or cracks in the release layer and
effectively prevent defects from being generated in a multi-layered
ceramic capacitor.
[0100] Further, according to this preferred embodiment, the spacer
layer is formed using the dielectric paste containing a binder
containing ethyl cellulose having a weight average molecular weight
of MW.sub.L and ethyl cellulose having a weight average molecular
weight of MW.sub.H at a weight ratio of X:(1-X), where MW.sub.L,
MW.sub.H and X are selected so that X*MW.sub.L+(1-X)*MW.sub.H falls
within a range of 110,000 to 180,000 and at least one solvent
selected from the group consisting of isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate and the solvent selected
from the group consisting of isobornyl acetate, dihydroterpinyl
methyl ether, dihydroterpinyl oxyethanol, terpinyl methyl ether,
terpinyl oxyethanol, d-dihydrocarveol, I-menthyl acetate,
I-citronellol, I-perillylalcohol and
acetoxy-methoxyethoxy-cyclohexanol acetate hardly dissolves an
acrylic system resin contained in a ceramic green sheet as a
binder. As a result, even in the case of forming a release layer
containing the same binder as that contained in the ceramic green
sheet and printing a dielectric paste on the surface of the release
layer, thereby forming a spacer layer, it is possible to
effectively prevent the release layer from being swollen or
partially dissolved so as to generate voids at the interface
between the release layer and the spacer layer or generate fissures
or wrinkles on the surface of the spacer layer. Therefore, in the
case where a multi-layered ceramic capacitor is fabricated by
laminating a number of multi-layered units each including a ceramic
green sheet and an electrode layer, it is possible to reliably
prevent voids from being generated in the multi-layered ceramic
capacitor and it is also possible to reliably prevent the portions
of the spacer layer where fissures or wrinkles are generated from
dropping off during lamination of a number of the multi-layered
units to fabricate the laminated body and mixing into the laminated
body as a foreign substance so as to cause internal defects in the
multi-layered ceramic capacitor.
[0101] Moreover, according to this preferred embodiment, since it
is possible to prevent the release layer from being swollen or
partially dissolved, thereby changing the release strength between
the release layer and the electrode layer and the spacer layer or
the release layer and the electrode layer, it is possible to
effectively prevent defects from being generated when a
multi-layered unit is fabricated.
[0102] In a further preferred embodiment, in the case where the
adhesive layer is transferred onto the surface of the electrode
layer or the surfaces of the electrode layer and the spacer layer,
an adhesive layer is transferred onto the surface of a ceramic
green sheet of a multi-layered unit fabricated by laminating a
release layer, an electrode layer or an electrode layer and a
spacer layer, an adhesive layer and a ceramic green sheet on a long
second support sheet and without cutting the multi-layered unit, a
release layer of another multi-layered unit fabricated by
laminating a ceramic green sheet, an adhesive layer, an electrode
layer or an electrode layer and a spacer layer, and the release
layer on a long support sheet is bonded onto the adhesive layer and
the support sheet is peeled off from the ceramic green sheet,
whereby two multi-layered units are laminated on the long second
support sheet.
[0103] Then, an adhesive layer formed on a third support sheet is
transferred onto the ceramic green sheet located on the side of the
surface of the laminated two multi-layered units and a release
layer of another multi-layered unit fabricated by laminating a
ceramic green sheet, an adhesive layer, an electrode layer or an
electrode layer and a spacer layer, and the release layer on a long
support sheet is bonded onto the adhesive layer and the support
sheet is peeled off from the release layer.
[0104] Similar processes are repeated, thereby fabricating a
multi-layered unit set including a predetermined number of
laminated multi-layered units. Further, an adhesive layer formed on
the third support sheet is transferred onto the surface of the
ceramic green sheet located on the side of the surface of the
multi-layered unit set, thereby fabricating a laminated body and
the laminated body is diced to predetermined dimensions, thereby
fabricating a multi-layered blocks.
[0105] On the other hand, in the case where the adhesive layer is
transferred onto the surface of the ceramic green sheet, an
adhesive layer is transferred onto the surface of a release layer
of a multi-layered unit fabricated by laminating a ceramic green
sheet, an adhesive layer, an electrode layer or an electrode layer
and a spacer layer, and the release layer on a long support sheet
and without cutting the multi-layered unit, a ceramic green sheet
of another multi-layered unit fabricated by laminating a release
layer, an electrode layer or an electrode layer and a spacer layer,
an adhesive layer and a ceramic green sheet on a long second
support sheet is bonded onto the adhesive layer and the second
support sheet is peeled off from the release layer, whereby two
multi-layered units are laminated on the long second support
sheet.
[0106] Then, an adhesive layer formed on a third support sheet is
transferred onto the release layer located on the side of the
surface of the laminated two multi-layered units and a ceramic
green sheet of a multi-layered unit fabricated by laminating a
release layer, an electrode layer or an electrode layer and a
spacer layer, an adhesive layer and a ceramic green sheet on a long
second support sheet is further laminated on the adhesive layer.
Then, the second support sheet is peeled off from the release
layer.
[0107] Similar processes are repeated, thereby fabricating a
multi-layered unit set including a predetermined number of
laminated multi-layered units. Further, an adhesive layer formed on
the third support sheet is transferred onto the surface of the
release layer located on the side of the surface of the
multi-layered unit set, thereby fabricating a laminated body and
the laminated body is diced to predetermined dimensions, thereby
fabricating multi-layered blocks.
[0108] A multi-layered ceramic capacitor is fabricated using the
thus fabricated multi-layered blocks in the manner of the previous
preferred embodiment.
[0109] According to this preferred embodiment, since the
multi-layered units are successively laminated on the long second
support sheet or support sheet, thereby fabricating the
multi-layered unit set including a predetermined number of
multi-layered units and the multi-layered unit set is diced to
predetermined dimensions, thereby fabricating multi-layered blocks,
it is possible to markedly improve the manufacturing efficiency of
the multi-layered blocks in comparison with the case where
multi-layered blocks are fabricated by laminating multi-layered
units each of which has been diced to predetermined dimensions.
[0110] In a further preferred embodiment of the present invention,
in the case where the adhesive layer is transferred onto the
surface of the electrode layer or the surfaces of the electrode
layer and the spacer layer, an adhesive layer is transferred onto
the surface of a ceramic green sheet of a multi-layered unit
fabricated by laminating a release layer, an electrode layer or an
electrode layer and a spacer layer, an adhesive layer and a ceramic
green sheet on a long second support sheet and without cutting the
multi-layered unit, an electrode layer or an electrode layer and a
spacer layer formed on the second support sheet are bonded onto the
adhesive layer and the second support sheet is peeled off from the
release layer, whereby the electrode layer and the spacer layer,
and the release layer are transferred onto the surface of the
adhesive layer.
[0111] Then, an adhesive layer formed on a third support sheet is
transferred onto the surface of the release layer transferred onto
the adhesive layer, a ceramic green sheet formed on the support
sheet is bonded onto the adhesive layer and the support sheet is
peeled off from the ceramic green sheet, whereby the ceramic green
sheet is transferred onto the surface of the adhesive layer.
[0112] Further, an adhesive layer formed on a third support sheet
is transferred onto the surface of the ceramic green sheet
transferred onto the surface of the adhesive layer, an electrode
layer or an electrode layer and a spacer layer formed on the second
support sheet are bonded onto the adhesive layer and the second
support sheet is peeled off from the release layer, whereby the
electrode layer or the electrode layer and the spacer layer, and
the release layer are transferred onto the surface of the adhesive
layer.
[0113] Similar processes are repeated, thereby fabricating a
multi-layered unit set including a predetermined number of
laminated multi-layered units. Further, an adhesive layer formed on
the third support sheet is transferred onto the surface of the
ceramic green sheet located on the side of the surface of the
multi-layered unit set, thereby fabricating a laminated body and
the laminated body is diced to predetermined dimensions, thereby
fabricating multi-layered blocks.
[0114] On the other hand, in the case where the adhesive layer is
transferred onto the surface of the ceramic green sheet, an
adhesive layer is transferred onto the surface of a release layer
of a multi-layered unit fabricated by laminating a ceramic green
sheet, an adhesive layer, an electrode layer or an electrode layer
and a spacer layer, and the release layer on a long support sheet
and without cutting the multi-layered unit, a ceramic green sheet
of a support sheet is bonded onto the adhesive layer and the
support sheet is peeled off from the ceramic green sheet, whereby
the ceramic green sheet is transferred onto the adhesive layer.
[0115] Further, an adhesive layer formed on the third support sheet
is transferred onto the ceramic green sheet transferred onto the
adhesive layer and an electrode layer or an electrode layer and a
spacer layer formed on the second support sheet are bonded onto the
adhesive layer. Then, the second support sheet is peeled off from
the release layer, whereby the electrode layer or the electrode
layer and the spacer layer, and the release layer are transferred
onto the surface of the adhesive layer.
[0116] Further, an adhesive layer formed on the third support sheet
is transferred onto the release layer transferred onto the adhesive
layer and a ceramic green sheet formed on the support sheet is
bonded onto the adhesive layer. Then, the support sheet is peeled
off from the ceramic green sheet, whereby the ceramic green sheet
is transferred onto the surface of the adhesive layer.
[0117] Similar processes are repeated, thereby fabricating a
multi-layered unit set including a predetermined number of
laminated multi-layered units. Further, an adhesive layer is
transferred onto the surface of the release layer located on the
side of the surface of the multi-layered unit set, thereby
fabricating a laminated body and the laminated body is diced to
predetermined dimensions, thereby fabricating multi-layered
blocks.
[0118] A multi-layered ceramic green sheet is fabricated using the
thus fabricated multi-layered block in the manner of the previous
embodiment.
[0119] According to this preferred embodiment, the transferring of
the adhesive layer, the transferring of the electrode layer or the
electrode layer and the spacer layer and the release layer, the
transferring of the adhesive layer and the transferring of the
ceramic green sheet onto the long second support sheet or support
sheet are repeated, thereby successively laminating the
multi-layered units to fabricate the multi-layered unit set
including a predetermined number of multi-layered units and the
multi-layered unit set is diced to predetermined dimensions,
thereby fabricating multi-layered blocks. As a result, it is
possible to markedly improve the manufacturing efficiency of the
multi-layered block in comparison with the case where multi-layered
blocks are fabricated by laminating multi-layered units each of
which has been diced to predetermined dimensions.
[0120] Hereinafter, working examples and comparative examples will
be set out in order to further clarify the advantages of the
present invention.
WORKING EXAMPLES
Working Example 1
Preparation of a Dielectric Paste for Forming a Ceramic Green
Sheet
[0121] 1.48 weight parts of (BaCa)SiO.sub.3, 1.01 weight parts of
Y.sub.2O.sub.3, 0.72 weight part of MgCO.sub.3, 0.13 weight part of
MnO and 0.045 weight part of V.sub.2O.sub.5 were mixed, thereby
preparing an additive powder.
[0122] 159.3 weight parts of ethyl cellulose and 0.93 weight parts
of polyethylene glycol system dispersing agent were added to 100
weight parts of the thus prepared additive powder to prepare a
slurry and the additives contained in the slurry were
pulverized.
[0123] When the additives contained in the slurry were to be
pulverized, 11.65 grams of the slurry and 450 grams of ZrO.sub.2
beads having a diameter of 2 mm were charged in a polyethylene
vessel having an inner volume of 250 cc and the polyethylene vessel
was rotated at the circumferential velocity of 45 m/min for sixteen
hours, thereby pulverizing the additive powder to prepare the
additive slurry.
[0124] The median diameter of the additives after pulverization was
0.1 .mu.m.
[0125] Then, 15 weight parts of a copolymer of methyl methacrylate
and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. was dissolved
into 85 weight parts of ethyl acetate at 50.degree. C., thereby
preparing an organic vehicle solution of 8%. Further, a slurry
having the composition set out below was mixed with the organic
vehicle solution for twenty hours using a polyethylene vessel
having an inner volume of 500 cc, thereby preparing a dielectric
paste. When the slurry was to be mixed with the organic vehicle
solution, 344.1 grams of the slurry and 900 grams of ZrO.sub.2
beads having a diameter of 2 mm were charged in the polyethylene
vessel and the polyethylene vessel was rotated at the
circumferential velocity of 45 m/min. TABLE-US-00001 BaTiO.sub.3
powder ("BT-02" (Product Name) 100 weight parts manufactured by
SAKAI CHEMICAL INDUSTRY CO., LTD.: particle diameter 0.2 .mu.m)
additive slurry 11.2 weight parts ethyl acetate 163.76 weight parts
toluene 21.48 weight parts polyethylene glycol system dispersing
agent 1.04 weight parts antistatic auxiliary agent 0.83 weight
parts diacetone alcohol 1.04 weight parts benzyl butyl phthalate
(plasticizing agent) 2.61 weight parts butyl stearate 0.52 weight
parts mineral sprit 6.78 weight parts organic vehicle 34.77 weight
parts
[0126] As a polyethylene glycol system dispersing agent, a
dispersing agent which was obtained by denaturing polyethylene
glycol with aliphatic acid and whose hydrophile-lipophile balance
(HLB) was 5 to 6 was employed and as an antistatic auxiliary agent,
polyethylene glycol whose average molecular weight was 400.
Formation of a Ceramic Green Sheet
[0127] A polyethylene terephthalate film was coated with the thus
prepared dielectric paste using a die coater at a coating velocity
of 50 m/minutes, thereby forming a coating layer and the thus
formed coating layer was dried in a drying furnace whose
temperature was held at 80.degree. C., thereby forming a ceramic
green sheet having a thickness of 1 .mu.m.
Preparation of a Conductive Paste for Forming an Electrode
Layer
[0128] 1.48 weight parts of (BaCa)SiO.sub.3, 1.01 weight parts of
Y.sub.2O.sub.3, 0.72 weight part of MgCO.sub.3, 0.13 weight part of
MnO and 0.045 weight part of V.sub.2O.sub.5 were mixed, thereby
preparing an additive powder.
[0129] 150 weight parts of acetone, 104.3 weight parts of isobornyl
acetate and 1.5 weight parts of polyethylene glycol system
dispersing agent were added to 100 weight parts of the thus
prepared additive powder to prepare a slurry and the additives
contained in the slurry were pulverized using a pulverizer "LMZ0.6"
(Product name) manufactured by Ashizawa Finetech Co., Ltd.
[0130] When the additives contained in the slurry were to be
pulverized, ZrO.sub.2 beads having a diameter of 0.1 mm were
charged into a vessel so as to occupy 80 volume % of the vessel,
the vessel was rotated at the circumferential velocity of 14 m/min
and the slurry was circulated between the vessel and a slurry tank
until holding time of the whole slurry of two liters became 30
minutes, thereby pulverizing the additives contained in the
slurry.
[0131] The median diameter of the additives after pulverization was
0.1 .mu.m.
[0132] Then, acetone was evaporated using an evaporator and removed
from the slurry, thereby preparing an additive paste in which the
additives were dispersed in terpineol. The concentration of the
additives contained in the additive paste was 49.3 weight %.
[0133] Then, 8 weight parts of a binder containing ethyl cellulose
having a weight average molecular weight (MW.sub.H) of 230,000 and
ethyl cellulose having a weight average molecular weight (MW.sub.L)
of 130,000 at a weight ratio of 75:25, namely, 8 weight parts of
ethyl cellulose having an apparent weight average molecular weight
of 205,000 defined as X*MW.sub.L+(1-X):*MW.sub.H, was dissolved in
92 weight parts of isobornyl acetate at 70.degree. C., thereby
preparing an 8% organic vehicle solution. Further, a slurry having
the composition set out below was dispersed in the organic vehicle
solution for sixteen hours using a ball mill. The dispersing
conditions were set so that the amount of charged ZrO.sub.2 having
a diameter of 2.0 mm was 30 volume % of the ball mill, the amount
of the slurry in the ball mill was 60 volume % and the
circumferential velocity of the ball mill was 45 m/min.
TABLE-US-00002 nickel powder manufactured by Kawatetsu 100 weight
parts Industry Co., Ltd. and having a particle diameter of 0.2
.mu.m additive paste 1.77 weight parts BaTiO.sub.3 powder
manufactured by 19.14 weight parts SAKAI CHEMICAL INDUSTRY CO.,
LTD. organic vehicle 56.25 weight parts polyethylene glycol system
dispersing agent 1.19 weight parts isobornyl acetate 32.19 weight
parts acetone 56 weight parts
[0134] Then, acetone was evaporated using a stirring device having
an evaporator and a heating mechanism and removed from the slurry,
thereby preparing a conductive paste. The concentration of the
dielectric material contained in the conductive paste was 47 weight
%.
[0135] The viscosity of the thus obtained conductive paste was
measured using a rheometer manufactured by HAAKE Co., Ltd. under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0136] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 19.4 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 10.4 Pss.
Formation of an Electrode Layer and Fabrication of a Multi-Layered
Unit
[0137] The thus prepared conductive paste was printed on the
ceramic green sheet using a screen printing machine and dried at
90.degree. C. for five minutes, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0138] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. As a result, it was found
that the surface roughness (Ra) of the electrode layer was 0.143
.mu.m and that the electrode layer having a high surface smoothness
was formed.
Fabrication of a Ceramic Green Chip
[0139] The surface of a polyethylene terephthalate film was coated
with the dielectric paste prepared in the above described manner
using a die coater, thereby forming a coating layer, and the
coating layer was dried, thereby forming a ceramic green sheet
having a thickness of 10 .mu.m.
[0140] The thus formed ceramic green sheet was peeled off from the
polyethylene terephthalate film and diced. Five of the diced
ceramic green sheet units were laminated to form a cover layer
having a thickness of 50 .mu.m. Further, the multi-layered unit was
peeled off from the polyethylene terephthalate film and diced and
fifty of the diced multi-layered units were laminated on the cover
layer.
[0141] Then, the ceramic green sheet having a thickness of 10 .mu.m
was peeled off from the polyethylene terephthalate film and diced
and five of the ceramic green sheet units were laminated on the
multi-layered units laminated on the cover layer, thereby
fabricating a laminated body including the lower cover layer having
a thickness of 50 .mu.m, an active layer having a thickness of 100
.mu.m and including the laminated fifty multi-layered units each
including the ceramic green sheet having a thickness of 1 .mu.m and
the electrode layer having a thickness of 1 .mu.m, and an upper
cover layer having a thickness of 50 .mu.m.
[0142] Further, a pressure of 100 MPa was applied onto the thus
fabricated laminated body at 70.degree. C., thereby press molding
the laminated body and the laminated body was diced to
predetermined dimensions using a dicing machine, thereby
fabricating ceramic green chips.
Fabrication of a Multi-Layered Ceramic Capacitor Sample
[0143] The thus fabricated ceramic green chip was processed under
the following conditions in an air atmosphere to remove the
binder.
[0144] Rate of temperature increase: 50.degree. C./hour
[0145] Holding temperature: 240.degree. C.
[0146] Holding time period: 8 hours
[0147] After removing the binder, the ceramic green chip was
processed and baked under the following conditions in a mixed gas
atmosphere of a nitrogen gas and a hydrogen gas whose temperature
was controlled at the dew point 20.degree. C. The contents of the
nitrogen gas and the hydrogen gas contained in the mixed gas were
95 volume % and 5 volume %, respectively.
[0148] Rate of temperature increase: 300.degree. C./hour
[0149] Holding temperature: 1200.degree. C.
[0150] Holding time period: 2 hours
[0151] Cooling rate: 300.degree. C./hour
[0152] The thus baked ceramic green chip was subjected to an
annealing treatment under the following conditions in a nitrogen
gas atmosphere whose temperature was controlled at the dew point
20.degree. C.
[0153] Rate of temperature increase: 300.degree. C./hour
[0154] Holding temperature: 1000.degree. C.
[0155] Holding time period: 3 hours
[0156] Cooling rate: 300.degree. C./hour
[0157] End surfaces of the thus obtained sintered body were
polished by the sandblast and coated with In--Ga alloy, thereby
forming a terminal electrode. Thus, a multi-layered ceramic
capacitor sample was fabricated.
[0158] A total of fifty multi-layered ceramic capacitor samples
were fabricated in a manner similar to the foregoing.
Measurement of a Short-Circuit Failure Ratio
[0159] The resistance value of each of the thus fabricated
multi-layered ceramic capacitor samples was measured using a
multi-meter to check whether or not short-circuit failure occurred
therein.
[0160] In the case where the thus measured resistance value was
equal to or lower than 100 K.OMEGA., it was judged that
short-circuit failure occurred in the multi-layered ceramic
capacitor sample. The number of the ceramic capacitor samples in
which short-circuit failure occurred was measured and the ratio of
the number of the ceramic capacitor samples in which short-circuit
failure occurred to the total number of the fabricated
multi-layered ceramic capacitor samples was calculated and defined
as the short-circuit failure ratio.
[0161] As a result, the short-circuit failure ratio of the
multi-layered ceramic capacitor samples was found to be 18%, so
that the risk of short-circuit failure could be considered
insignificant from the practical viewpoint.
Working Example 2
[0162] A conductive paste was prepared in the manner of Working
Example 1 except that a binder containing ethyl cellulose having a
weight average molecular weight (MW.sub.H) of 230,000 and ethyl
cellulose having a weight average molecular weight (MW.sub.L) of
130,000 at a weight ratio of 50:50, namely, ethyl cellulose having
an apparent weight average molecular weight of 180,000 defined as
X*MW.sub.L+(1-X):*MW.sub.H, was used and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0163] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 15.5 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 8.5 Pss.
[0164] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0165] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.088 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0166] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 8%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 3
[0167] A conductive paste was prepared in the manner of Working
Example 1 except that a binder containing ethyl cellulose having a
weight average molecular weight (MW.sub.H) of 230,000 and ethyl
cellulose having a weight average molecular weight (MW.sub.L) of
130,000 at a weight ratio of 25:75, namely, ethyl cellulose having
an apparent weight average molecular weight of 155,000 defined as
X*MW.sub.L+(1-X):*MW.sub.H, was used and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0168] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 11.2 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.8 Pss.
[0169] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0170] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.065 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0171] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 6%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 4
[0172] A conductive paste was prepared in the manner of Working
Example 1 except that dihydroterpinyl methyl ether was used as a
solvent instead of isobornyl acetate and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0173] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 16.1 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 9.3 Pss.
[0174] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0175] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.132 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0176] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 16%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 5
[0177] A conductive paste was prepared in the manner of Working
Example 4 except that a binder containing ethyl cellulose having a
weight average molecular weight (MW.sub.H) of 230,000 and ethyl
cellulose having a weight average molecular weight (MW.sub.L) of
130,000 at a weight ratio of 50:50 was used and the viscosity of
the thus prepared conductive paste was measured under conditions of
a temperature of 25.degree. C. and shearing velocity of 8
sec.sup.-1 and was also measured under conditions of a temperature
of 25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0178] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 12.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 7.3 Pss.
[0179] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0180] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.070 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0181] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 12%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 6
[0182] A conductive paste was prepared in the manner of Working
Example 4 except that a binder containing ethyl cellulose having a
weight average molecular weight (MW.sub.H) of 230,000 and ethyl
cellulose having a weight average molecular weight (MW.sub.L) of
130,000 at a weight ratio of 25:75 was used and the viscosity of
the thus prepared conductive paste was measured under conditions of
a temperature of 25.degree. C. and shearing velocity of 8
sec.sup.-1 and was also measured under conditions of a temperature
of 25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0183] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 8.6 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 5.3 Pss.
[0184] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0185] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.068 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0186] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 12%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 7
[0187] A conductive paste was prepared in the manner of Working
Example 1 except that dihydroterpinyl oxyethanol was used as a
solvent instead of isobornyl acetate and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0188] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 16.6 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 9.6 Pss.
[0189] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0190] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory. Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.133 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0191] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 18%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 8
[0192] A conductive paste was prepared in the manner of Working
Example 3 except that dihydroterpinyl oxyethanol was used as a
solvent instead of isobornyl acetate and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0193] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 13.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 7.7 Pss.
[0194] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0195] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.072 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0196] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 20%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 9
[0197] A conductive paste was prepared in the manner of Working
Example 3 except that dihydroterpinyl oxyethanol was used as a
solvent instead of isobornyl acetate and the viscosity of the thus
prepared conductive paste was measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 8 sec.sup.-1
and was also measured under conditions of a temperature of
25.degree. C. and shearing velocity of 50 sec.sup.-1.
[0198] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 8.9 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 5.2 Pss.
[0199] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0200] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.081 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0201] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 14%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 10
[0202] A conductive paste was prepared in the manner of Working
Example 1 except that terpinyl methyl ether was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0203] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 16.2 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 9.4 Pss.
[0204] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0205] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.115 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0206] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 18%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 11
[0207] A conductive paste was prepared in the manner of Working
Example 2 except that terpinyl methyl ether was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0208] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 11.7 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.6 Pss.
[0209] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0210] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.068 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0211] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 10%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 12
[0212] A conductive paste was prepared in the manner of Working
Example 3 except that terpinyl methyl ether was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0213] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 8.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 4.9 Pss.
[0214] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0215] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.060 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0216] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 14%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 13
[0217] A conductive paste was prepared in the manner of Working
Example 2 except that terpinyl oxyethanol was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0218] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 10.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.2 Pss.
[0219] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0220] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.071 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0221] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 16%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 14
[0222] A conductive paste was prepared in the manner of Working
Example 2 except that d-dihydrocarveol was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0223] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 10.6 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.0 Pss.
[0224] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0225] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.075 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0226] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 18%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 15
[0227] A conductive paste was prepared in the manner of Working
Example 2 except that I-menthyl acetate was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0228] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 10.6 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 5.8 Pss.
[0229] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0230] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.071 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0231] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 14%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 16
[0232] A conductive paste was prepared in the manner of Working
Example 2 except that I-citronellol was used as a solvent instead
of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0233] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 10.8 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.2 Pss.
[0234] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0235] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.069 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0236] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 16%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 17
[0237] A conductive paste was prepared in the manner of Working
Example 2 except that I-perillylalcohol was used as a solvent
instead of isobornyl acetate and the viscosity of the thus prepared
conductive paste was measured under conditions of a temperature of
25.degree. C. and shearing velocity of 8 sec.sup.-1 and was also
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 50 sec.sup.-1.
[0238] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 11.5 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.4 Pss.
[0239] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0240] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.072 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0241] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 20%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Working Example 18
[0242] A conductive paste was prepared in the manner of Working
Example 2 except that acetoxy-methoxyethoxy-cyclohexanol acetate
was used as a solvent instead of isobornyl acetate and the
viscosity of the thus prepared conductive paste was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0243] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 16.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 8.9 Pss.
[0244] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0245] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.078 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0246] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 18%, so that the risk of
short-circuit failure could be considered insignificant from the
practical viewpoint.
Comparative Example 1
[0247] A conductive paste was prepared in the manner of Working
Example 1 except that ethyl cellulose having a weight average
molecular weight of 230,000 was used as a binder of a conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0248] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 23.2 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 12.1 Pss.
[0249] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0250] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.230 .mu.m, that is, the surface
roughness of the electrode layer was high, so that an electrode
layer having a high surface smoothness could not be formed.
[0251] It was reasonable to conclude that this was because the
viscosity of the conductive paste at the shearing velocity of 50
sec.sup.-1 was too high to print the conductive paste in a desired
manner.
[0252] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 36% and it was found that
the short-circuit failure was very high.
Comparative Example 2
[0253] A conductive paste was prepared in the manner of Working
Example 1 except that ethyl cellulose having a weight average
molecular weight of 130,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0254] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 7.1 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 4.7 Pss.
[0255] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0256] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.070 .mu.m, i.e., that the surface
smoothness of the electrode layer was high. However, it was found
that since the viscosity of the conductive paste at the shearing
velocity of 50 sec.sup.-1 was too low and the fluidity of the
conductive paste was too high, the conductive paste leaked from a
screen printing plate and the electrode layer could not be formed
in a desired pattern.
Comparative Example 3
[0257] A dielectric paste for forming a ceramic green sheet was
prepared in the manner of Working Example 1 except that a copolymer
of methyl methacrylate and butyl acrylate whose acid value was 5
mgKOH/gram, copolymerization ratio (weight ratio) was 82:18,
weight-average molecular weight was 230,000 and Tg was 70.degree.
C. was used as a binder of the dielectric paste for forming a
ceramic green sheet, thereby forming a ceramic green sheet.
[0258] Further, a conductive paste was prepared in the manner of
Working Example 2 and the viscosity of the thus prepared dielectric
paste for forming a ceramic green sheet was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0259] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 15.5 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 9.8 Pss.
[0260] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0261] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.112 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0262] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in the manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 36% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0263] It is reasonable to conclude that this was because the
weight-average molecular weight of the binder of the dielectric
paste for forming the ceramic green sheet was 230,000, which is too
low, so that part of the ceramic green sheet was swollen and
dissolved by the solvent.
Comparative Example 4
[0264] A conductive paste was prepared in the manner of Working
Example 4 except that ethyl cellulose having a weight average
molecular weight of 230,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0265] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 20.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 11.3 Pss.
[0266] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0267] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.221 .mu.m and that since the
surface roughness of the electrode layer was too high, the
electrode layer having a high surface smoothness could not be
formed.
[0268] It was reasonable to conclude that this was because the
viscosity of the conductive paste at the shearing velocity of 50
sec.sup.-1 was too high to print the conductive paste in a desired
manner.
[0269] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 38% and it was found that
the short-circuit failure was very high.
Comparative Example 5
[0270] A conductive paste was prepared in the manner of Working
Example 4 except that ethyl cellulose having a weight average
molecular weight of 130,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0271] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 5.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 3.2 Pss.
[0272] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0273] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.066 .mu.m and that the surface
smoothness of the electrode layer was high. However, it was found
that since the viscosity of the conductive paste at the shearing
velocity of 50 sec.sup.-1 was too low and the fluidity of the
conductive paste was too high, the conductive paste leaked from a
screen printing plate and the electrode layer could not be formed
in a desired pattern.
Comparative Example 6
[0274] A dielectric paste for forming a ceramic green sheet was
prepared in the manner of Working Example 1 except that a copolymer
of methyl methacrylate and butyl acrylate whose weight-average
molecular weight was 230,000, copolymerization ratio (weight ratio)
was 82:18 and Tg was 70.degree. C. was used as a binder of a
dielectric paste for forming a ceramic green sheet, thereby forming
a ceramic green sheet.
[0275] Further, a conductive paste was prepared in the manner of
Working Example 5 and the viscosity of the thus prepared dielectric
paste for forming a ceramic green sheet was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0276] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 12.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 7.3 Pss.
[0277] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0278] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.120 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0279] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 34% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0280] It is reasonable to conclude that this was because the
weight-average molecular weight of the binder of the dielectric
paste for forming a ceramic green sheet was 230,000, which was too
low, so that part of the ceramic green sheet was swollen and
dissolved by the solvent.
Comparative Example 7
[0281] A conductive paste was prepared in the manner of Working
Example 7 except that ethyl cellulose having a weight average
molecular weight of 230,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0282] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 21.1 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 11.9 Pss.
[0283] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0284] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.241 .mu.m and that since the
surface roughness of the electrode layer was too high, the
electrode layer having a high surface smoothness could not be
formed.
[0285] It was reasonable to conclude that this was because the
viscosity of the conductive paste at the shearing velocity of 50
sec.sup.-1 was too high to print the conductive paste in a desired
manner.
[0286] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 40% and it was found that
the short-circuit failure was very high.
Comparative Example 8
[0287] A conductive paste was prepared in the manner of Working
Example 7 except that ethyl cellulose having a weight average
molecular weight of 130,000 was used as a binder of a conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0288] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 5.5 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 3.1 Pss.
[0289] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0290] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.069 .mu.m and that the surface
smoothness of the electrode layer was high. However, it was found
that since the viscosity of the conductive paste at the shearing
velocity of 50 sec.sup.-1 was too low and the fluidity of the
conductive paste was too high, the conductive paste leaked from a
screen printing plate and the electrode layer could not be printed
in a desired manner.
Comparative Example 9
[0291] A dielectric paste for forming a ceramic green sheet was
prepared in the manner of Working Example 1 except that a copolymer
of methyl methacrylate and butyl acrylate whose weight-average
molecular weight was 230,000, copolymerization ratio (weight ratio)
was 82:18, and Tg was 70.degree. C. was used as a binder of a
dielectric paste for forming a ceramic green sheet, thereby forming
a ceramic green sheet.
[0292] Further, a conductive paste was prepared in the manner of
Working Example 8 and the viscosity of the thus prepared dielectric
paste for forming a ceramic green sheet was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0293] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 13.3 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 7.7 Pss.
[0294] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0295] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.145 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0296] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 42% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0297] It is reasonable to conclude that this was because the
weight-average molecular weight of the binder of the dielectric
paste for forming a ceramic green sheet was 230,000, which was too
low, so that part of the ceramic green sheet was swollen and
dissolved by the solvent.
Comparative Example 10
[0298] A conductive paste was prepared in the manner of Working
Example 10 except that ethyl cellulose having a weight average
molecular weight of 230,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0299] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 20.5 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 11.8 Pss.
[0300] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0301] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.221 .mu.m and that since the
surface roughness of the electrode layer was too high, the
electrode layer having a high surface smoothness could not be
formed.
[0302] It was reasonable to conclude that this was because the
viscosity of the conductive paste at the shearing velocity of 50
sec.sup.-1 was too high to print the conductive paste in a desired
manner.
[0303] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 39% and it was found that
the short-circuit failure was very high.
Comparative Example 11
[0304] A conductive paste was prepared in the manner of Working
Example 10 except that ethyl cellulose having a weight average
molecular weight of 130,000 was used as a binder of the conductive
paste and the viscosity of the thus prepared conductive paste was
measured under conditions of a temperature of 25.degree. C. and
shearing velocity of 8 sec.sup.-1 and was also measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 50 sec.sup.-1.
[0305] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 5.2 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 3.0 Pss.
[0306] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0307] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.063 .mu.m and that the surface
smoothness of the electrode layer was high. However, it was found
that since the viscosity of the conductive paste at the shearing
velocity of 50 sec.sup.-1 was too low and the fluidity of the
conductive paste was too high, the conductive paste leaked from a
screen printing plate and the electrode layer could not be formed
in a desired pattern.
Comparative Example 12
[0308] A dielectric paste for forming a ceramic green sheet was
prepared in the manner of Working Example 1 except that a copolymer
of methyl methacrylate and butyl acrylate whose weight-average
molecular weight was 230,000, copolymerization ratio (weight ratio)
was 82:18, and Tg was 70.degree. C. was used as a binder of a
dielectric paste for forming a ceramic green sheet, thereby forming
a ceramic green sheet.
[0309] Further, a conductive paste was prepared in the manner of
Working Example 11 and the viscosity of the thus prepared
dielectric paste for forming a ceramic green sheet was measured
under conditions of a temperature of 25.degree. C. and shearing
velocity of 8 sec.sup.-1 and was also measured under conditions of
a temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0310] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 11.7 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.6 Pss.
[0311] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0312] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.189 .mu.m.
[0313] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 56% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0314] It is reasonable to conclude that this was because the
weight-average molecular weight of the binder of the dielectric
paste for forming a ceramic green sheet was 230,000, which was too
low, so that part of the ceramic green sheet was swollen and
dissolved by the solvent
Comparative Example 13
[0315] A conductive paste was prepared in the manner of Comparative
Example 2 except that a mixed solvent of terpineol and kerosene
(mixture ratio (mass ratio) of 50:50) was used instead of isobornyl
acetate as the solvent for preparing the conductive paste and the
viscosity of the thus prepared conductive paste was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0316] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 10.7 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.7 Pss.
[0317] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0318] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.130 .mu.m and that the electrode
layer having a high surface smoothness was formed.
[0319] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 46% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0320] It is reasonable to conclude that this was because the mixed
solvent of terpineol and kerosene used as a solvent of the
conductive paste dissolved a copolymer of methyl methacrylate and
butyl acrylate used as the binder of the ceramic green sheet.
Comparative Example 14
[0321] A conductive paste was prepared in the manner of Comparative
Example 2 except that terpineol was used instead of isobornyl
acetate as the solvent for preparing the conductive paste and the
viscosity of the thus prepared conductive paste was measured under
conditions of a temperature of 25.degree. C. and shearing velocity
of 8 sec.sup.-1 and was also measured under conditions of a
temperature of 25.degree. C. and shearing velocity of 50
sec.sup.-1.
[0322] As a result, it was found that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 8 sec.sup.-1 was 13.1 Pss and that the viscosity of the
conductive paste measured under condition of the shearing velocity
of 50 sec.sup.-1 was 6.9 Pss.
[0323] Then, the thus prepared conductive paste was printed on a
ceramic green sheet fabricated in the manner of Working Example 1
using a screen printing machine, thereby forming an electrode layer
having a thickness of 1 .mu.m. Thus, a multi-layered unit including
the ceramic green sheet and the electrode layer laminated on the
polyethylene terephthalate film was fabricated.
[0324] The surface roughness (Ra) of the thus formed electrode
layer was measured using the "SURFCORDER (SE-30D)" (Product Name)
manufactured by Kosaka Laboratory Ltd. in the manner of Working
Example 1. As a result, it was found that the surface roughness
(Ra) of the electrode layer was 0.192 .mu.m and that since the
surface roughness of the electrode layer was too high, the
electrode layer having a high surface smoothness could not be
formed.
[0325] It is reasonable to conclude that this was because terpineol
used as a solvent of the conductive paste dissolved a copolymer of
methyl methacrylate and butyl acrylate used as the binder of the
ceramic green sheet.
[0326] Further, a total of fifty multi-layered ceramic capacitor
samples were fabricated and the resistance value of each of the
thus fabricated multi-layered ceramic capacitor samples was
measured using a multi-meter in a manner of Working Example 1 to
check whether or not short-circuit failure occurred therein. As a
result, the short-circuit failure ratio of the multi-layered
ceramic capacitor samples was found to be 76% and it was found that
the short-circuit failure was so high that the samples were of no
practical use.
[0327] It is reasonable to conclude that this was because terpineol
used as a solvent of the conductive paste dissolved a copolymer of
methyl methacrylate and butyl acrylate used as the binder of the
ceramic green sheet.
[0328] It was found from Working Examples 1 to 18 and Comparative
Examples 13 and 14 that in the case where the conductive paste
containing ethyl cellulose having a weight average molecular weight
of 130,000 as a binder and the mixed solvent of terpineol and
kerosene (mixture ratio (mass ratio) of 50:50) as a solvent or the
conductive paste containing ethyl cellulose having a weight average
molecular weight of 130,000 as a binder and terpineol as a solvent
was printed on the ceramic green sheet formed by using the
dielectric paste containing a copolymer of methyl methacrylate and
butyl acrylate whose acid value was 5 mgKOH/gram, copolymerization
ratio (weight ratio) was 82:18, weight-average molecular weight was
450,000 and Tg was 70.degree. C. as a binder, thereby fabricating
the multi-layered unit, and fifty of the multi-layered units were
laminated, thereby fabricating the multi-layered ceramic capacitor,
the solvent of the conductive paste dissolved a copolymer of methyl
methacrylate and butyl acrylate contained in the ceramic green
sheet as a binder, so that the ceramic green sheet was swollen or
partially dissolved, thereby generating pinholes or cracks in the
ceramic green sheet and causing the short-circuit failure ratio of
the multi-layered ceramic capacitors to become extremely high,
while in the case where the conductive paste containing ethyl
cellulose having an apparent weight average molecular weight of
155,000 to 205,000 defined by X*MW.sub.L+(1-X)*MW.sub.H as a binder
and isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol or acetoxy-methoxyethoxy-cyclohexanol acetate as
a solvent was printed on the ceramic green sheet formed by using
the dielectric paste containing a copolymer of methyl methacrylate
and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. as a binder,
thereby fabricating the multi-layered unit, and fifty of the
multi-layered units were laminated, thereby fabricating the
multi-layered ceramic capacitor, the solvent of the conductive
paste hardly dissolved a copolymer of methyl methacrylate and butyl
acrylate contained in the ceramic green sheet as a binder, so that
the ceramic green sheet was not swollen or partially dissolved,
thereby preventing generation of pinholes or cracks in the ceramic
green sheet and markedly decreasing the short-circuit failure ratio
of the multi-layered ceramic capacitors.
[0329] Further, it was found from Working Examples 1 to 18 and
Comparative Examples 1, 4, 7 and 10 that in the case where the
conductive paste containing ethyl cellulose having a weight average
molecular weight of 230,000 as a binder and isobornyl acetate as a
solvent, the conductive paste containing ethyl cellulose having a
weight average molecular weight of 230,000 as a binder and
dihydroterpinyl methyl ether as a solvent, the conductive paste
containing ethyl cellulose having a weight average molecular weight
of 230,000 as a binder and dihydroterpinyl oxyethanol as a solvent
or the conductive paste containing ethyl cellulose having a weight
average molecular weight of 230,000 as a binder and terpinyl methyl
ether as a solvent was printed on the ceramic green sheet formed by
using the dielectric paste containing a copolymer of methyl
methacrylate and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. as a binder,
thereby fabricating the multi-layered unit, and fifty of the
multi-layered units were laminated, thereby fabricating the
multi-layered ceramic capacitor, the viscosity of the conductive
paste was so high that it was impossible to print the conductive
paste on the ceramic green sheet in a desired manner to form an
electric layer having a high surface smoothness, so that the
short-circuit failure ratio of the multi-layered ceramic capacitors
became extremely high, while in the case where the conductive paste
containing ethyl cellulose having an apparent weight average
molecular weight of 155,000 to 205,000 defined by
X*MW.sub.L+(1-X)*MW.sub.H as a binder and isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol or
acetoxy-methoxyethoxy-cyclohexanol acetate as a solvent was printed
on the ceramic green sheet formed by using the dielectric paste
containing a copolymer of methyl methacrylate and butyl acrylate
whose acid value was 5 mgKOH/gram, copolymerization ratio (weight
ratio) was 82:18, weight-average molecular weight was 450,000 and
Tg was 70.degree. C. as a binder, thereby fabricating the
multi-layered unit, and fifty of the multi-layered units were
laminated, thereby fabricating the multi-layered ceramic capacitor,
the conductive paste had a viscosity suitable for printing, so that
it was possible to form an electric layer on a ceramic green sheet
in a predetermined pattern using a screen printing machine in a
desired manner and fabricate multi-layered ceramic capacitors whose
short-circuit failure ratio was low.
[0330] Furthermore, it was found from Working Examples 1 to 18 and
Comparative Examples 2, 5, 8 and 11 that in the case where the
conductive paste containing ethyl cellulose having a weight average
molecular weight of 130,000 as a binder and isobornyl acetate as a
solvent, the conductive paste containing ethyl cellulose having a
weight average molecular weight of 130,000 as a binder and
dihydroterpinyl methyl ether as a solvent, the conductive paste
containing ethyl cellulose having a weight average molecular weight
of 130,000 as a binder and dihydroterpinyl oxyethanol as a solvent
or the conductive paste containing ethyl cellulose having a weight
average molecular weight of 130,000 as a binder and terpinyl methyl
ether as a solvent was printed on the ceramic green sheet formed by
using the dielectric paste containing a copolymer of methyl
methacrylate and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. as a binder,
thereby fabricating the multi-layered unit, the viscosity of the
conductive paste was too low and the fluidity of the conductive
paste was too high, so that the conductive paste leaked from a
screen printing plate and the electrode layer could not be formed
in a desired pattern, while in the case where the conductive paste
containing ethyl cellulose having an apparent weight average
molecular weight of 155,000 to 205,000 defined by
X*MW.sub.L+(1-X)*MW.sub.H as a binder and isobornyl acetate,
dihydroterpinyl methyl ether, dihydroterpinyl oxyethanol, terpinyl
methyl ether, terpinyl oxyethanol, d-dihydrocarveol, I-menthyl
acetate, I-citronellol, I-perillylalcohol or
acetoxy-methoxyethoxy-cyclohexanol acetate as a solvent was printed
on the ceramic green sheet formed by using the dielectric paste
containing a copolymer of methyl methacrylate and butyl acrylate
whose acid value was 5 mgKOH/gram, copolymerization ratio (weight
ratio) was 82:18, weight-average molecular weight was 450,000 and
Tg was 70.degree. C. as a binder, thereby fabricating the
multi-layered unit, and fifty of the multi-layered units were
laminated, thereby fabricating the multi-layered ceramic capacitor,
the conductive paste had a viscosity suitable for printing, so that
it was possible to form an electric layer on a ceramic green sheet
in a predetermined pattern using a screen printing machine in a
desired manner and fabricate multi-layered ceramic capacitors whose
short-circuit failure ratio was low.
[0331] Moreover, it was found from Working Examples 1 to 18 and
Comparative Examples 3, 6 and 9 that in the case where the
conductive paste containing ethyl cellulose having an apparent
weight average molecular weight of 180,000 as a binder and
isobornyl acetate as a solvent, the conductive paste containing
ethyl cellulose having an apparent weight average molecular weight
of 180,000 as a binder and dihydroterpinyl methyl ether as a
solvent, the conductive paste containing ethyl cellulose having an
apparent weight average molecular weight of 180,000 as a binder and
dihydroterpinyl oxyethanol as a solvent or the conductive paste
containing ethyl cellulose having an apparent weight average
molecular weight of 180,000 as a binder and terpinyl methyl ether
as a solvent was printed on the ceramic green sheet formed by using
the dielectric paste containing a copolymer of methyl methacrylate
and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. as a binder,
thereby fabricating the multi-layered unit, the short-circuit
failure ratio of the multi-layered ceramic capacitors became very
high, while in the case where the conductive paste containing ethyl
cellulose having an apparent weight average molecular weight of
155,000 to 205,000 defined by X*MW.sub.L+(1-X)*MW.sub.H as a binder
and isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol or acetoxy-methoxyethoxy-cyclohexanol acetate as
a solvent was printed on the ceramic green sheet formed by using
the dielectric paste containing a copolymer of methyl methacrylate
and butyl acrylate whose acid value was 5 mgKOH/gram,
copolymerization ratio (weight ratio) was 82:18, weight-average
molecular weight was 450,000 and Tg was 70.degree. C. as a binder,
thereby fabricating the multi-layered unit, and fifty of the
multi-layered units were laminated, thereby fabricating the
multi-layered ceramic capacitor, the short-circuit failure ratio of
the multi-layered ceramic capacitors markedly decreased. It is
reasonable to assume that this was because the weight-average
molecular weight of the binder of the dielectric paste for forming
a ceramic green sheet was 230,000, which is too low, so that part
of the ceramic green sheet was swollen and dissolved by the
solvent.
[0332] Further, it was found that in the case where a dielectric
paste adapted for forming a spacer layer and containing ethyl
cellulose having an apparent weight average molecular weight of
110,000 to 180,000 defined by X*MW.sub.L+(1-X)*MW.sub.H as a binder
and isobornyl acetate, dihydroterpinyl methyl ether,
dihydroterpinyl oxyethanol, terpinyl methyl ether, terpinyl
oxyethanol, d-dihydrocarveol, I-menthyl acetate, I-citronellol,
I-perillylalcohol or acetoxy-methoxyethoxy-cyclohexanol acetate as
a solvent was prepared and the dielectric paste was printed on the
ceramic green sheet in a complimentary pattern to that of the
electrode layer, thereby forming a spacer layer, the same results
as those above were obtained.
[0333] The present invention has thus been shown and described with
reference to the preferred embodiments and the working examples.
However, it should be noted that the present invention is in no way
limited to the details of the described arrangement but changes and
modifications may be made without departing from the scope of the
appended claims.
[0334] According to the present invention, it is possible to
provide a conductive paste for a multi-layered ceramic electronic
component which does not dissolve a binder contained in a layer
adjacent to an electrode layer of the multi-layered ceramic
electronic component, can reliably prevent short circuit failure
from occurring in a multi-layered ceramic electronic component and
has excellent printability.
[0335] Further, according to the present invention, it is possible
to provide a method for manufacturing a multi-layered unit for a
multi-layered ceramic electronic component which can reliably
prevent short circuit failure from occurring in a multi-layered
ceramic electronic component and form an electrode layer in a
desired manner.
* * * * *